1. Field of the Invention
The present invention relates to modular broach and handle assemblies for use in orthopedic implant surgery. More particularly, the present invention relates to a modular broach handle construction featuring a locking mechanism for the broach that can be operated by surgeon without any special manipulative steps. The locking mechanism includes a trigger that moves a slider bar out of engagement with the broach so the handle can easily be disconnected and a spring that allows the handle to be locked onto the broach by simply pushing the components together.
2. General Background
Releasable broach or rasp handles have been used for the purpose of supporting a rasp in preparing a bone for receiving an implant. The handle is preferably releasable from the rasp following such use so other instruments can be used in preparing the bone while the portion inside the bone remains in place during other steps.
Typically, the broach or rasp is used during hip arthroplasty. The surgeon uses the broach to prepare the inner surfaces of the intermedullary canal to receive the stem of a femoral hip prosthesis. Surgical preparation of the intermedullary canal determines in large part the fit between the stem and femur and the accuracy of alignment.
The upper end of the broach is typically designed so other instruments can fit on it to prepare the upper surface of the femur. By using the broach as the reference point, accurate orientation of the prosthesis relative to the prepared bone is easier to achieve. A surgeon can also attach a trial neck and head to the upper end of the broach for performing a reduction in order to check range of motion, muscle tension, and leg length. Since hip surgery is a potentially dangerous and serious procedure, these instruments must be designed to provide a dependable connection that is easy to disengage.
Releasable broach or rasp and handle constructions have been developed in the past. Examples are shown in U.S Pat. No. 4,306,550, issued to Forte entitled "Combination Including Femoral Rasp And Calcar Facing Reamer"; U.S. Pat. No. 4,583,270, issued to Kenna, entitled "Rasp Handle"; and U.S. Pat. No. 4,601,289, issued to Chiarizzio et al., entitled "Femoral Trail Prosthesis/Rasp Assembly".
The Forte '550 patent provides a construction which includes a rasp having a cutting portion and a pilot post portion. A handle assembly with a chuck releasably engages the pilot post portion to facilitate working the rasp into a femur. A cutter device is adapted to be journaled on the pilot post and power driven to prepare the surface of the calcar adjacent the socket. After a socket is formed in the femur by use of a rasp and handle assembly, the rasp is left in the socket, the handle assembly is removed, and the cutter is journaled over the pilot post and rotated by a drive apparatus. However, the handle includes an enlongated transverse portion which extends away from the longitudinal axis of the handle. A transverse portion of this style, while workable, requires two hands to operate and extra manipulation to move the portion away from the handle.
The Kenna '270 patent includes a similar laterally extending portion of the handle. In the Chiarizzio et al. patent, a locking portion must pivot to a lateral position in order to disengage the broach from the handle, possibly interfering with other surgical instruments. These above-discussed patented devices require a preliminary manipulation of the locking mechanism in order to affix the broach to the handle.